The higher harmonics of the free electron laser(FEL)with a two-wavenumber plane wiggler magnetic field,which may induce a lot of higher harmonics,are investigated.Using a two-wavenumber wiggler comprised of two separa...The higher harmonics of the free electron laser(FEL)with a two-wavenumber plane wiggler magnetic field,which may induce a lot of higher harmonics,are investigated.Using a two-wavenumber wiggler comprised of two separate periodicities,k_(ω)and k_(ω)+Δk,numerical simulations show that the higher harmonic may be amplified and the first harmonic may be suppressed in this kind of FEL with an optimized parameterΔk.The coupling coefficient and gain coefficient in low-gain regime of the harmonic are also obtained.展开更多
Following a single-particle approach,a detailed analysis of the higher harmonic in free electron laser(FEL)with combined electromagnetic wiggler and axial guide magnetic fields is derived.The spontaneous emission spec...Following a single-particle approach,a detailed analysis of the higher harmonic in free electron laser(FEL)with combined electromagnetic wiggler and axial guide magnetic fields is derived.The spontaneous emission spectrum and the gain in the low-gain Compton regime are also calculated in detail.This analysis results in a clear resonance condition and shows that this kind of FEL can generate significant coherent harmonic emission of radiation with axial guide magnetic field of suitable strength.展开更多
The motion of a charged particle in tokamak magnetic field whose Larmor radius po is not much smaller than the typical length Lq is studied in slab model by solving the equations of motion analytically,where L_(B)=|B/...The motion of a charged particle in tokamak magnetic field whose Larmor radius po is not much smaller than the typical length Lq is studied in slab model by solving the equations of motion analytically,where L_(B)=|B/ΔB|.It is found that drift can still be predicted by the drift approximation,but gyration depends largely on the variation of the magnetic field over Larmor radius and the initial motion parameters.In the case of Po/Lq 1,our results show their agreements with the previous work.展开更多
The small-signal linear gain for a combined electromagnetic wiggler and an axial-guide magnetic field free electron laser is derived within the presence of beam equilibrium self-fields.The numerical results show that ...The small-signal linear gain for a combined electromagnetic wiggler and an axial-guide magnetic field free electron laser is derived within the presence of beam equilibrium self-fields.The numerical results show that the gain is reduced as the self-fields increase.展开更多
A set of coupled equations for electron motion and the dispersion relation of electromagnetic wave(wiggler)in electron beam are studied.The instability of steady-state electron orbits is reduced to the problem of the ...A set of coupled equations for electron motion and the dispersion relation of electromagnetic wave(wiggler)in electron beam are studied.The instability of steady-state electron orbits is reduced to the problem of the fourth-order and fifth-order linear ordinary differential equations.It is found that the presence of self-fields plays an important role in determining the behaviour of stable electron orbits.展开更多
Objective:To investigate the adjusting malnutrition mechanism by the Reinforcing Kidney and Exhausting Toxic Mixture(REM)on the chronic renal failure (CRF) rat.Methods:60 wistar rats weved ivided into 3 groups randoml...Objective:To investigate the adjusting malnutrition mechanism by the Reinforcing Kidney and Exhausting Toxic Mixture(REM)on the chronic renal failure (CRF) rat.Methods:60 wistar rats weved ivided into 3 groups randomly :the normal controc group(group Ⅰ),CRF group(group Ⅱ),and CRF rat perfusingwithREM group(group Ⅲ). Taking theirfat,kidneytissuefor detecting the protein expression of the leptin,leptin receptor(Ob-R) by the means ofimmunohistochemistry.Result:Comparing with control group, the leptinprotein express intensely in CRF rat ; In kidney tissue,the ob-R express weakly. After perfusing the REM ,comparing with CRF groupthe renal ob-R express strongly than CRF group. Conclusion: Maybe the REM could do a little better with the malnutritionof CRFratsby adjusttingthe activity of ob-R in kidney.展开更多
Developing high sensitive organic semiconductors(OSCs)in organic thin-film transistors(OTFTs)is the key for OTFT based gas sensors.Herein,we report a simple processing route of highly sensitive OSCs for high performan...Developing high sensitive organic semiconductors(OSCs)in organic thin-film transistors(OTFTs)is the key for OTFT based gas sensors.Herein,we report a simple processing route of highly sensitive OSCs for high performance OTFT based nitrogen dioxide(NO2)sensors,where the active OSC layer is based on ultraviolet-ozone(UVO)treated poly(3-hexylthiophene-2,5-diyl)(P3HT).Compared to conventional P3HT based OTFT sensors,the reported device exhibits a remarkable improvement of the gas response from 350%to 30000%.The studies in morphologies,chemical compositions and microstructures of the UVOtreated films reveal that a large number of carrier traps generated in the P3HT films is the decisive reason for the enhancement of sensing performance.Moreover,the optimized device shows great potential of practical applications on the stand points of sensitivity,selectivity,reusability and the ability of recovery,as well as limit of detection of~7.3 ppb.This simple method provides an innovative understanding for the role of the carrier traps in sensing performance and demonstrates a bright future for developing high performance OTFT gas sensors.展开更多
Axially displaced elliptical （ADE） antenna is an evolved version of Gregorian antenna, bearing advantages of minimized blockage and relatively uniform field distribution. However, the analysis of the electrical perf...Axially displaced elliptical （ADE） antenna is an evolved version of Gregorian antenna, bearing advantages of minimized blockage and relatively uniform field distribution. However, the analysis of the electrical performance of this type of antenna is a difficulty to be addressed properly. To enable the simulation of such type of reflector antenna, a hybrid method is derived for predicting the farfield of ADE antennas. Closed formulae are firstly derived for the calculation of the near field of ADE antennas based on vector analysis and the law of energy conservation. These formulae avoid time-consuming surface current integration and the current singularity on the vertex of the sub-reflector. In addition, the nature of vector analysis makes the hybrid method be capable of predicting vector electric field precisely. Furthermore, since these formulae are in explicit manner, no ray tracing process is required. The farfield is then predicted using Huygens equivalent method, assuring the accuracy in the farfield. Compared to published experimental results in the literature, the proposed method agrees well with the measurement in the main beam region. In comparison to physical optic method, the computational efficiency is much improved.展开更多
文摘The higher harmonics of the free electron laser(FEL)with a two-wavenumber plane wiggler magnetic field,which may induce a lot of higher harmonics,are investigated.Using a two-wavenumber wiggler comprised of two separate periodicities,k_(ω)and k_(ω)+Δk,numerical simulations show that the higher harmonic may be amplified and the first harmonic may be suppressed in this kind of FEL with an optimized parameterΔk.The coupling coefficient and gain coefficient in low-gain regime of the harmonic are also obtained.
文摘Following a single-particle approach,a detailed analysis of the higher harmonic in free electron laser(FEL)with combined electromagnetic wiggler and axial guide magnetic fields is derived.The spontaneous emission spectrum and the gain in the low-gain Compton regime are also calculated in detail.This analysis results in a clear resonance condition and shows that this kind of FEL can generate significant coherent harmonic emission of radiation with axial guide magnetic field of suitable strength.
文摘The motion of a charged particle in tokamak magnetic field whose Larmor radius po is not much smaller than the typical length Lq is studied in slab model by solving the equations of motion analytically,where L_(B)=|B/ΔB|.It is found that drift can still be predicted by the drift approximation,but gyration depends largely on the variation of the magnetic field over Larmor radius and the initial motion parameters.In the case of Po/Lq 1,our results show their agreements with the previous work.
文摘The small-signal linear gain for a combined electromagnetic wiggler and an axial-guide magnetic field free electron laser is derived within the presence of beam equilibrium self-fields.The numerical results show that the gain is reduced as the self-fields increase.
文摘A set of coupled equations for electron motion and the dispersion relation of electromagnetic wave(wiggler)in electron beam are studied.The instability of steady-state electron orbits is reduced to the problem of the fourth-order and fifth-order linear ordinary differential equations.It is found that the presence of self-fields plays an important role in determining the behaviour of stable electron orbits.
文摘Objective:To investigate the adjusting malnutrition mechanism by the Reinforcing Kidney and Exhausting Toxic Mixture(REM)on the chronic renal failure (CRF) rat.Methods:60 wistar rats weved ivided into 3 groups randomly :the normal controc group(group Ⅰ),CRF group(group Ⅱ),and CRF rat perfusingwithREM group(group Ⅲ). Taking theirfat,kidneytissuefor detecting the protein expression of the leptin,leptin receptor(Ob-R) by the means ofimmunohistochemistry.Result:Comparing with control group, the leptinprotein express intensely in CRF rat ; In kidney tissue,the ob-R express weakly. After perfusing the REM ,comparing with CRF groupthe renal ob-R express strongly than CRF group. Conclusion: Maybe the REM could do a little better with the malnutritionof CRFratsby adjusttingthe activity of ob-R in kidney.
基金supported by the National Natural Science Foundation of China(Grant Nos.61421002,61675041,51703019&31771079)the National Key R&D Program of China(Grant No.2018YFB0407102)+2 种基金the Project of Science and Technology of Sichuan Province(Grant Nos.2020YFG0281,2019YFG0121&2020YFG0279)City University of Hong Kong(Grant No.9610423)sponsored by Sichuan Province Key Laboratory of Display Science and Technology。
文摘Developing high sensitive organic semiconductors(OSCs)in organic thin-film transistors(OTFTs)is the key for OTFT based gas sensors.Herein,we report a simple processing route of highly sensitive OSCs for high performance OTFT based nitrogen dioxide(NO2)sensors,where the active OSC layer is based on ultraviolet-ozone(UVO)treated poly(3-hexylthiophene-2,5-diyl)(P3HT).Compared to conventional P3HT based OTFT sensors,the reported device exhibits a remarkable improvement of the gas response from 350%to 30000%.The studies in morphologies,chemical compositions and microstructures of the UVOtreated films reveal that a large number of carrier traps generated in the P3HT films is the decisive reason for the enhancement of sensing performance.Moreover,the optimized device shows great potential of practical applications on the stand points of sensitivity,selectivity,reusability and the ability of recovery,as well as limit of detection of~7.3 ppb.This simple method provides an innovative understanding for the role of the carrier traps in sensing performance and demonstrates a bright future for developing high performance OTFT gas sensors.
基金supported by the National Natural Science Foundation of China (61401031)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘Axially displaced elliptical （ADE） antenna is an evolved version of Gregorian antenna, bearing advantages of minimized blockage and relatively uniform field distribution. However, the analysis of the electrical performance of this type of antenna is a difficulty to be addressed properly. To enable the simulation of such type of reflector antenna, a hybrid method is derived for predicting the farfield of ADE antennas. Closed formulae are firstly derived for the calculation of the near field of ADE antennas based on vector analysis and the law of energy conservation. These formulae avoid time-consuming surface current integration and the current singularity on the vertex of the sub-reflector. In addition, the nature of vector analysis makes the hybrid method be capable of predicting vector electric field precisely. Furthermore, since these formulae are in explicit manner, no ray tracing process is required. The farfield is then predicted using Huygens equivalent method, assuring the accuracy in the farfield. Compared to published experimental results in the literature, the proposed method agrees well with the measurement in the main beam region. In comparison to physical optic method, the computational efficiency is much improved.
